The present invention relates to a supported superconductor device which is useful as a superconducting current lead or as a high voltage current regulator.
In its most general embodiment, the invention provides a supported superconducting device comprising a tubular support with a first layer of ceramic, glassy or glass ceramic material adhered to the inner wall of the tubular support and embedding a superconducting layer centrally arranged within the support.
The first layer material is reinforced with pore filling material of a suitable low viscous and self curing property, including polymeric organic material, in particular, epoxy resins.
Materials convenient for use as the embedding material in the first layer are preferably selected from inorganic material with minimal thermal expansion coefficient, including ceramic material of the cordierite type or glassy material, in particular, quartz or lithium alumina silicate glass.
The above materials are able to transfer compression force from the tubular support to the superconducting layer.
The superconducting layer may consist of any of the known brittle superconductors, in particular, high temperature superconductors.
The invention concerns furthermore a method of supporting a ceramic superconductor using a porous material in a perforated tube. Terminals of an electrical conducting material are connected at each end of the tube. The superconductor material is arranged inside the tube and is soldered to the two terminals. The space between tube and superconductor is filled with a porous material allowing liquid or gas to diffuse into the superconducting material through the perforations in the tube and the pore in the porous material. The superconducting material may be in form a centrally arranged superconductive rod or elongated plate.
The tube may be formed of metal, glass, ceramics, polymer or composites thereof. The perforations in the tube may be of various shapes and sizes.
The terminals are made from electrically conducting material, such as steel, copper, silver, gold or other metals or alloys. The terminals are connected to the tube ends by glueing, screwing them into the tube, or using screws. Preferably, at least one of the terminals is provided with a hole, allowing the superconducting material to be introduced into the tube and soldered to the terminals.
In order to obtain low contact resistance between the superconductor and the terminals, the superconductor is preferably coated with silver. The superconductor is introduced into the tube and soldered to the contacts.
As a major advantage of the invention, the supported superconductor allows to connect large electrical terminals to the superconducting material without stressing the material by adhering the terminals to the tubular support prior to installation of the superconducting material.
Porous filler material may be produced by coating particles (metals, glass, ceramics or polymers) with a binder or mixing the particles and binder with an amount of binder which is less than the volume between the packed particles. The particles are mixed with the binder prior to introducing the filler material into the tube or after introduction of the material into the tube. Thereby, gas or liquid is able to diffuse to the superconducting material through the perforations in the tube and further through the pores in the filler material.
The superconducting material is mechanically supported by the filler material and the tube. The supporting tube and filler material may be made electrically insulating by employing electrical insulating material for the manufacture of the tube and the filler. The support may be an electrical conductor in the form of a conducting tube and/or particle and binder system. The above superconductor device may be used in combination with forced flow cooling, which allows the use of a higher quench current without damaging the superconductor as compared with a non-porous support.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.